The present invention relates, in general, to vehicle navigation systems and methods, and more specifically, to a system and method for indicating information relating to a next intersection to be turned at for a vehicle operator such as a driver of an automotive vehicle.
In recent years, demands for navigation systems equipped in automotive vehicles have rapidly increased due to complexity of the roads (especially in city areas) and drivers' desires for smooth flowing transportation. However, as availability of navigation systems increases, drivers having insufficient familiarity with the systems and displays increasingly becomes a problem. Therefore, a navigation system which allows anyone to easily and safely reach their destination by showing a route to the driver in an highly recognizable way is desired.
For easily recognizable and accurate route guidance, U.S. Pat. No. 5,416,478 discloses that numerical characters are added to designated intersections in a map of the route displayed on a main monitor device. The numerical character and a direction (left, right or straight) to go at the next designated intersection are also shown on display just in front of the driver which is independent from the main monitor device, and these indications are changed as the vehicle passes the designated intersection. In this patent, however, the driver has to see the map on the main monitor device in order to know how long or how far he must travel to get to the next intersection to be turned at. This is very inconvenient, because it is difficult to find out, from the map, the relative distance between the current position and the next intersection or time duration to reach the next intersection from the current position.
For providing more recognizable information to the driver, in U.S. Pat. Nos. 5,323,321 and 5,587,911, it is disclosed that the remaining distance to the next intersection to be turned at is shown with actual numerical characters, such as 130 meters.
FIG. 7 shows an example of a display according to the concept of the prior art disclosed in the '321 and '911 patents. An indication 41 of the display shows 130 meters from a present position to the next intersection to be turned at. An indication 42 of the display shows an actual name of the intersecting street to be turned on. A curved line 43 indicates a direction to be turned at the intersection.
There is still inconvenience to the driver in this prior art, for it is difficult to know how far the actual distance such as 130 meters is while driving the automotive vehicle just relying on the driver's own sense of distance. Thus, it is difficult for the driver to identify the next intersection well prior to the intersection so as to turn without confusion. Particularly in the case that two adjacent intersections are in close proximity, the distance between them might be smaller than an error of the vehicle position monitoring system, such as the global positioning system (GPS). From only the relative distance information, one cannot exactly determine which of the intersections is to be turned at because of the error of the positioning system.
To solve this problem, one could provide image information, such as photographs, relating to the next intersection by reproducing image data stored in a memory device of the system, such as disclosed in U.S. Pat. No. 4,937,751, for example. However, as a practical matter, the large amount of image data requires a much larger data memory than does conventional map data. If the amount of the image data is reduced so as to minimize memory requirements, the driver cannot obtain sufficiently useful information. For example, the image of the intersection could be stored for only one direction of approach to the intersection. Thus, the images may be confusing when approaching the intersection from a different direction. If the amount of image data is not limited in this fashion, the system may need such an amount of time to retrieve and process the data for the display that it is difficult to supply the proper information to the driver prior to the time of the desired actual turn at the intersection.